**Summary**
- Fixed Ruby warning about unescaped closing bracket in character class
within `MENTION_REGEX`
- Properly escaped the `]` character in the regex pattern to follow Ruby
regex syntax standards
**Changes**
- Updated `MENTION_REGEX` in `lib/regex_helper.rb` to escape the closing
bracket in character class `[^]]+` → `[^\\]]+`
b8814a8bd5